This invention relates generally to a dynamic magnetic information storage record medium and more specifically to a coating process wherein the substrate is treated for the magnetic layer.
1. Field of the Invention
Magnetic recording media having thin films of a magnetizable metal or alloys thereof have found a usage in the electronic data processing equipment as high storage capacity memories. Various forms of the substrate base such as films, drums, wires or disks are commonly used. The thin film metal plated magnetic recording media permits a higher storage capacity from the usual iron oxide recording media.
Generally the magnetic layer is deposited onto a substrate that is easily machinable such as an aluminum disk. But aluminum contains impurities that hinder fabricating the perfectly smooth surface required for the magnetic layer and a low flying magnetic recording transducer. Further, a galvanic action can occur between the aluminum substrate and the thin film magnetizable layer if the magnetizable layer is deposited directly onto the substrate. The galvanic action causes a corrosion of a subsequent layer and thereby causes recording errors. A synthetic substance layer solves these problems but the synthetic materials are highly gas-evolving, with a consequence of an embrittlement of the subsequent layers. The function of the present invention is to solve the problem of the use of a synthetic substance as a magnetic record carrier.
2. Description of the Prior Art
It is well known to insert different film layers between a substrate and a magnetic material layer. U.S. Pat. No. 3,116,159 to R. D. Fisher et al discloses a heat curable adhesive layer formed on a non-metallic substrate such as a polyethylene terephthalate material. The heat curable adhesive layer is a resin coating that is chemically activated to enable the substrate to receive the subsequent magnetic layer. U.S. Pat. No. 3,414,430 issued to Charles Maho, discloses the vacuum evaporation of a magnetic coating directly to a subbing layer of a synthetic elastomer which is used as an adhesive layer. The adhesive is deposited over a polyethylene terephethalate substrate. The synthetic elastomer is modified with a diisocyanate for improved smoothness.
It is also known to manufacturer a magnetic recording media by depositing an undercoat copper layer over the substrate treated by coating with an adhesive layer consisting of a dispersion of particulate iron or zinc in a binder as disclosed in U.S. Pat. No. 3,730,852 to A. Diebold et al. A ferromagnetic coating can then be deposited onto the copper undercoat layer. The copper deposition is made such that the copper exchanges the iron or zinc particles in the adhesive layer.
It is well known to insert a metal film between a substrate and a magnetic material layer. In the U.S. Pat. No. 3,150,939 to J. W. Wenner, a bonded nuclei metallized layer is bonded to a dielectric resin substrate. The magnetic layer is then deposited over the metallic undercoat layer. It is also known, as shown in the U.S. Pat. No. 3,520,664, to D. P. York, that a plurality of layers can be deposited intermediate the substrate and the magnetic layer. In the York Patent, a metallic oxide is deposited as an adhesive layer over a substrate which may be a dielectric or a conductive material. A dielectric film is deposited over the adhesive layer as an insulating layer. A metallic nucleating layer is then deposited to enhance the magnetic properties of the magnetic layer deposited onto the nucleating layer.
The prior art was sufficient for the undercoating of the magnetic layers used prior to present day technology. With the low flying transducers presently in usage, the magnetic layer must be ultra smooth. The use of a metallic undercoat to the magnetic layer for its enhancement is well known. However, this layer in itself is not sufficient to isolate the magnetic layer from the deficiencies of the synthetic substance layer. The intermediate layer to the nucleating metallic film of a York patent, for instance, does not present the resistivity required for the use in a data storage system, as the insulation layer as shown in the York patent is extremely brittle so that during processing or during use, there can appear surface fissures or cracks. Such deficiencies may not affect the magnetic thin film device as shown for use in York, but these deficiences in the magnetizable layer of a memory record can cause data errors during writing or reading the record carrier.
It is, therefore, an object of the present invention to provide a magnetic disk structure wherein a resin layer is provided as a protective layer for the substrate, with a layer of a getter metal as an insulation to a magnetic enhancing layer and a magnetic layer.